Pluging command exportFolders as jex

[JackGruber]

I am trying to export a folder in a plugin with the following command:

await joplin.commands.execute('exportFolders', 'e84fe96ee4a34f6eb1fd79105f29a772', "jex", export_path);

For md, raw and html it works fine, but for jex i get the following error:
Uncaught (in promise) Error: Cannot load "exporter" module for format "jex" and target "directory"